‘Wavering’ El Niño vexes winter weather outlook

Posted on October 22, 2012 by Bob Berwyn

Not much drought relief expected this winter.

NOAA calls for warmer-than-average conditions in the West

By Summit Voice

SUMMIT COUNTY —This year’s wavering El Niño isn’t just vexing Colorado forecasters. Forecasters with the National Oceanic and Atmospheric Administration say that getting a handle on the winter forecast has been tough.

“This is one of the most challenging outlooks we’ve produced in recent years because El Niño decided not to show up as expected,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “In fact, it stalled out last month, leaving neutral conditions in place in the tropical Pacific.” (more…)

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Colorado: Forecasters still grappling with winter outlook

Posted on October 17, 2012 by Bob Berwyn

An El Niño often brings decent October precipitation to the high country, but signals are mixed this year.

No clear signal means water managers will be biting their nails for a few months

By Bob Berwyn

FRISCO — Without a strong El Niño or La Niña signal, Colorado weather watchers are struggling even more than usual to get a sense of how much snow to expect this coming winter, critical information for water managers who have seen reservoir storage dwindle to below 70 percent of average for this time of year.

Even if winter snowfall is close to normal, some reservoirs are unlikely to refill completely next spring, leaving utilities in the position of hoping for an above average winter.

“We’re far from through this. The story has yet to unfold,” Blue River Basin water commissioner Troy Wineland said after participating in a weekly statewide water webinar, explaining that many local streams are flowing well below seasonal averages. A few others are close to average due to upstream releases of stored water, he said. (more…)

Filed under: climate and weather, Colorado, El Niño, La Niña, seasons, Snow and weather, Summit County snow and weather | Tagged: , , , , , | 2 Comments »

Weather: El Niño, or La Niña’s ghost?

Posted on October 8, 2012 by Bob Berwyn

El Niño still struggling to develop

Will a negative Pacific Decadal Oscillation influence Colorado’s winter weather? Graphic courtesy NASA.

The three-month precipitation outlook from the Climate Prediction Center.

By Bob Berwyn

SUMMIT COUNTY — Climate experts are still hedging their bets when it comes to an outlook for the coming winter, with the official outlook from NOAA’s Climate Prediction Center showing no strong trend toward above- or below-average precipitation.

A somewhat murky El Niño outlook is clouding the picture, with sea surface temperatures in the equatorial Pacific ranging above average, but cooling down from just a month ago.

“It’s vexing … the models are just not up to the task,” Wolter said. Overall, he said he’s “guardedly optimistic” that Colorado will see at least close to an average snowfall year, which would would be critical to maintaining water supplies in the state’s depleted reservoirs. (more…)

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Global warming drives extreme rainfall in the tropics

Posted on September 18, 2012 by Bob Berwyn

Researchers estimate 10 percent increase in rainfall during extreme events for every 1-degree Celsius of warming

Rainfall amounts during extreme weather events in the tropics are expected to increase by 10 percent for every 1-degree Celsius rise in temperatures. Photo by Bob Berwyn.

By Summit Voice

SUMMIT COUNTY — Researchers at MIT say extreme rainfall in the Earth’s tropical regions appear to be more sensitive to global warming than other parts of the world. While they don’t fully understand the mechanism for that higher sensitivity, they estimate that rainfall amounts during extreme weather events — monsoons, thunderstorms and tropical cyclones — are likely to increase by 10 percent for every 1-degree Celsius increase in temperatures.

“The study includes some populous countries that are vulnerable to climate change … and impacts of changes in rainfall could be important there,” said Paul O’Gorman, assistant professor of Atmospheric Science at MIT.

In general, most climate models agree that a warming atmosphere hold more water vapor. When storm systems develop, the increased humidity prompts heavier rain events that become more extreme as the climate warms. (more…)

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Colorado: Does El Niño bring early snow?

Posted on August 27, 2012 by Bob Berwyn

Historical stats don’t show big impact on date of first snow

Summit County and a small surrounding area dodged the drought bullet in late July and early August, with rainfall anywhere from 130 to 200 percent of normal, but rainfall maps show that most of the state still experienced well-below average rainfall during that span.

A similar pattern was evident for the three-month precipitation history in Colorado, with just a few pockets of above-average rainfall in the north-central mountains and the western San Juans.

SUMMIT COUNTY — Talk about living in a bubble — the latest three-month summary and outlook from the National Weather Service in Boulder shows that the rainy conditions in Summit County, and a small surrounding area, were the exception in Colorado the past 30 days. Much of the state continued to suffer through extremely dry conditions, especially the eastern plains, where precipitation was just 5 to 50 percent of normal. As a result, much of the state is still experiencing serious drought. Visit the Boulder NWS website to see the full power point presentation. (more…)

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Colorado: Will El Niño be a drought buster?

Posted on July 20, 2012 by Bob Berwyn

Drought likely to persist for several more months

The National Climatic Data Center temperature map for June 2012 clearly shows the extraordinary heat centered over Colorado.

By Summit Voice

SUMMIT COUNTY — A tilt toward El Niño conditions in the Pacific Ocean could start putting a dent in the western drought, according to the latest update from the Western Water Assessment climate summary.

El Niño, when sea surface temperatures in the equatorial Pacific climb above average, can help deliver average to above-average summer and fall moisture to Colorado and the Intermountain West, including drought-busting September rains in 2003 that helped end Colorado’s last serious drought.

El Niño doesn’t guarantee a wet winter. During many previous episodes, mid-winter conditions have been relatively dry, as the main storm track dives far to the south. But springtime during an El Niño phase can deliver copious precipitation to the Front Range and to the mountains along, and just east of, the Continental Divide.

The climate summary for June 2012 draws a number of comparisons to conditions in 2002, when conditions were even more dry across parts of western Colorado.

2002 extreme drought conditions were more widespread across Colorado than they are this year.

(more…)

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Goodbye La Niña — are you ready for El Niño?

Posted on July 19, 2012 by Bob Berwyn

Impacts on Colorado uncertain

Warmer-than-average sea surface temperatures are spreading west from the coast of South America, potentially heralding a developing El Niño.

The three-month precipitation outlook from NOAA’s Climate Prediction Center highlights a chance for above-average moisture in the Southeast and a small arc of the Southwest.

By Bob Berwyn

SUMMIT COUNTY — A classic El Niño may be developing across the eastern Pacific, with warmer-than-average water temperatures starting to spread westward from the coast of South America, according to NOAA’s Climate Prediction Center.

For the month of June, the pattern of sea surface temperatures overall remained in a neutral phase, but with growing positive (warmer than average) equatorial Pacific sea surface temperature anomalies, NOAA has issued an El Niño watch, reflecting a likely emergence of of El Niño in the late summer or fall. (more…)

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Climate: New research may enable earlier El Niño forecasts

Posted on June 26, 2012 by Bob Berwyn

Most El Niños since 1958 began with a previously unidentified subsurface discharge of warm water about 18 months before the peak of the events

A NOAA graph of June 25 sea surface temperature anomalies shows a spear of warm water spreading east from South America along the equator.

By Summit Voice

SUMMIT COUNTY — Not every El Niño is the same, but all of them start with a massive discharge of sub-surface warm water from the equatorial western Pacific.

That discharge starts much earlier than previously recognized, and may provide an early warning for the onset of El Niños, which can affect much of the world with weather anomalies, including flooding rains in some places and drought in other areas. It’s also seen as a mechanism for recharging the tropics with warm water.

The new El Niño study was authored by Nandini Ramesh and Raghu Murtugudd, associated with the University of New South Wales Climate Change Research Centre and published in the journal Nature Climate Change.

The scientists studied El Niño episodes between 1958 and 2011 to try and find a pattern. In the process, they showed that El Niños in the 1980s and 1990s started with warm sea surface temperature anomalies near the dateline that spread eastward, while earlier episodes started with anomalies off the west coast of South America and spread to the west. (more…)

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El Niño not good for dwindling leatherback sea turtles

Posted on May 24, 2012 by Bob Berwyn

Leatherback sea turtle closeup. Photo by Scott R. Benson, NMFS Southwest Fisheries Science Center.

Study suggests global warming will add to pressure on wide-ranging reptiles

By Summit Voice

SUMMIT COUNTY — Along with weather woes like droughts or excessive moisture, El Niño has been linked with higher mortality rates in populations of critically endangered leatherback sea turtles.

Those impacts could be exacerbated by global warming, may lead to more frequent warm and dry spells in key breeding areas like Northwest Costa Rica, according to researchers with Drexel University.

“Climate change may threaten survival of leatherback populations even if other factors driving population declines are removed,” the researchers wrote in a paper published online in the open access journal PLoS ONE. (more…)

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Colorado: A little snow history

Posted on April 15, 2012 by Bob Berwyn

Snowfall maps tell the tale of La Niña – El Niño cycles

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SUMMIT COUNTY — Each year’s weather triggers discussions about past seasons, and without having exact statistics at hand, it’s easy to get mixed up about snowfall records or dry spells. Last year, for example, during the big La Niña snows, there was a lot of talk about the “snowiest winter ever” and a lot of hype. More on the ENSO cycle here.

It was a big year, for sure, and the snow fell late into the spring, but detailed month-to-month comparisons from previous seasons showed that it wasn’t quite the snowiest year ever, though some specific locations did set snowfall records, for example at A-Basin, which reported record April totals. Which brings up another point: Snowfall totals can vary greatly across just very short distances, based on local topography and other factors. (more…)

Filed under: climate and weather, Colorado, El Niño, La Niña, Snow and weather, Summit County snow and weather | Tagged: , , , , , | 1 Comment »

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